1. Field of the Invention
The present invention relates to a programming system fitted with CRT, and more particularly to a system which is utilized for effecting programming of a programmable controller.
2. Description of the Prior Art
Heretofore, an usual programmable controller 28 has had such a construction as illustrated in FIG. 1. Namely, the programmable controller (PC) 28 comprises a central processing unit (CPU) 30, a sequence programming memory 34, a PC control programming ROM 36, a controlling RAM 38, a process input image memory 40, a process output image memory 42, a PSE interfacial part 32 for connecting the programmable controller to a programming system fitted with CRT (PSE) 10, and the like. A sequential program for the aforesaid PC 28 has previously been prepared by means of the PSE 10. Further a construction of the PSE 10 is also illustrated in FIG. 1. Namely, the PSE 10 comprises a CPU 12, a control programming ROM 14, a controlling RAM 16, a CRT controller 18, a CRT 20, a keyboard controller 22, a keyboard 24, a PC interfacial part 26, and the like. And the aforesaid PC 28 is suitably connected with the aforesaid PSE 10 by means of a connecting cable 44 at the time of loading a program upon the PC 28, monitoring the operational condition of the PC 28, effecting the simulation, and the like occasions.
Operation of the PC 28 will be described in detail hereinbelow.
Namely, the PC 28 is generally connected to an objective unit to be controlled and is operated by means of input and output 46 and 48 while transmitting signal (In this case, the connecting cable 44 shown in FIG. 1 has not been connected) so that the PC 28 itself comes to be installed in the locale.
The PC 28 is operated in accordance with the sequential program prepared by a user, and such program has been inputted in the memory 34. In the circumstances, the PC 28 effects the operation at the CPU 30 in accordance with the input 46 on the basis of the program inputted in the memory 34 while being controlled by means of the ROM 36, and controls the object to be controlled in accordance with the output 48. As a result, the RAM 38 acts as a temporary memory device for registration and the like of the CPU 30.
Next, operation of the PSE 10 will be described in detail hereinbelow.
The PSE 10 possesses such functions that prepares a program to be inputted in the memory 34 in the PC 28 and loads the program through the connecting cable 44, that monitors the operational condition of the PC 28, that effects simulation of the PC 28, and the like functions. In this connection, the connecting cable 44 is connected to the PC 28 in the case where it is intended to operate such functions as mentioned above.
Further the PSE 10 obtains input from the keyboard 24 and carries out the operation in the CPU 12 while being controlled by means of the ROM 14 so that the PSE 10 displays the state on that occasion in the CRT 20. The RAM 16 operates for registration and the like similarly to the RAM 38.
In addition, in the programming system illustrated in FIG. 1, the PSE 10 which does not involve a memory for sequential program is shown, but such a system involving a memory corresponding to the memory 34 in the PC 28 is also available on the market.
Meanwhile, operational simulation of the aforesaid PC 28 must be carried out in order to debug such sequential program by the use of the aforesaid PSE 10. In such a case, a conventional system has been operated in such a way, as illustrated in FIG. 1, that an actual process input 46 and a process output 48 of the PC 28 are not inputted and outputted into the system, but the contents of the process input image memory 40 and the controlling RAM 38 in the PC 28 are rewritten by means of the keyboard 24 in the PSE 10. According to such arrangements, the conventional system displays the operational status on the picture of the CRT 20 in the PSE, thereby to confirm, such operation.
In the conventional system as described above, however, the PSE 10 must have actually been connected to the PC 28 main body in order to carry out operational simulation of the aforesaid PC 28 by means of the PSE 10. For this reason, it has been difficult to effect debugging of such sequential program on the top of a desk or the like. On the other hand, the greatest possible care is required for such debugging work of program so that if such working cannot be practised on the top of a desk or the like, it is very inconvenient in view of such debugging work.